The falcon eyes cbh-12-4 clamps allows you to convert your light stand into a background system suitable for hanging up to 4 background rolls. in order to hang a background roll from the cbh-12-4, a bracket set such as the falcon eyes b-reel, must be purchased and used in conjunction therewith. alternatively, 4 crossbars can be used to hang your desired background. Each clamp has a length of 18cm and can be mounted upon any universal light stand. if you wish to use 4 background rolls with this set, a sturdy light stand will need to be used. please see the optional accessories tab below to view the compatible options. Please note: the light stand, crossbar and roll holders shown in the photos are not included with the cbh-12-4.